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BACKGROUND: Mortality caused by various pyrethroids, and neonicotinoids has been studied for stored-product insects in the past, yet limited information exists on the sublethal effects they can induce to Oryzaephilus surinamensis. In the current study, the sublethal effects of deltamethrin, λ-cyhalothrin, α-cypermethrin, etofenprox, and the mixture of acetamiprid with d-tetramethrin and piperonyl butoxide on the mobility of O. surinamensis in the presence or the absence of a food source was investigated. RESULTS: Lethal concentrations (LCs) were lower for deltamethrin, α-cypermethrin, and λ-cyhalothrin (LC10 = 0.000233, 0.000211, and 0.000271 mg active ingredient (a.i.) cm-2, LC30 = 0.000413, 0.000398, and 0.000447 mg a.i. cm-2, respectively), followed by etofenprox, and the mixture of acetamiprid with d-tetramethrin and piperonyl butoxide (LC10 = 0.00228 and 0.003267 mg a.i. cm-2, LC30 = 0.00437 and 0.01188 mg a.i. cm-2, respectively). Deltamethrin and λ-cyhalothrin negatively impacted adult walking behavior, increasing stop durations compared to controls. Adults exposed to LC10 and LC30 of λ-cyhalothrin, and LC30 of deltamethrin exhibited prolonged periods on their backs compared to the remaining treatments and the controls. The α-cypermethrin LC30-exposed adults exhibited significantly shorter walking and stopping durations than controls but demonstrated prolonged climbing on the arena walls compared to adults exposed to the remaining a.i. and the control. A similar trend was observed for etofenprox. CONCLUSIONS: Under sublethal concentrations, λ-cyhalothrin and deltamethrin increased stop intervals and reduced the duration of climbing attempts of O. surinamensis versus α-cypermethrin. These findings advance comprehension of the underexplored sublethal impacts of the tested a.i. on O. surinamensis adults, holding potential for leveraging insecticide-induced behavioral effects to enhance warehouse pest management. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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Phosphine (PH3) has been widely used as a fumigant in food storage, but increasing PH3 resistance in major pests makes finding alternative fumigants urgent. Methyl benzoate (MBe), a volatile organic compound regarded to be a food-safe natural product, has recently demonstrated significant toxicity against a variety of insect pests. This study is the first evaluation of the fumigation toxicity of three benzoate compounds, MBe, vinyl benzoate, and ethyl benzoate, against PH3-susceptible and PH3-resistant strains of Rhyzopertha dominica and Sitophilus oryzae. All strains were exposed to the compounds at concentrations up to 20 µL/1.5 L air for 24 h. Compared to vinyl benzoate and ethyl benzoate, MBe induced higher mortality rates in all strains at all concentrations. When food was made available, the lethal median concentration for MBe was 10-17-fold higher than when tested without food. Moreover, no significant differences were observed between the responses of the PH3-susceptible and PH3-resistant strains to the compounds. Notably, S. oryzae was more susceptible to MBe. In laboratory settings, MBe successfully controlled PH3-resistant strains of R. dominica and S. oryzae, making it a viable option for PH3-resistance management. Thus, MBe might be suitable for food security programs as an environmentally benign alternative fumigant.

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We evaluated the persistence and efficacy of two different, in granulometry and content of diatoms, diatomaceous earth (DE) formulations (i.e., DE5 and DE6), against two major beetle species of stored products, i.e., Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae). The formulations were applied as powders in soft wheat and maize in two doses of 500 and 1000 mg kg-1 (ppm). Samples of the treated grains were taken on the day of application and every 30 days until completion of the six-month period of storage. Adults of S. oryzae and R. dominica were exposed to the treated grains at 25 °C and 55% relative humidity, and the mortality was measured after 7, 14, and 21 days of exposure. Rhyzopertha dominica survival was not affected by any combination of DE formulation, dose, and commodity. Contrariwise, the DEs caused significant adult mortality of S. oryzae, in most of the cases tested. We observed that DE6 was equally effective in both wheat and maize, and no considerable variations were observed in S. oryzae mortality during the 6-month experimental period. Furthermore, DE6 was more effective against S. oryzae than DE5, a difference that could have potentially contributed to the variations in the diatom granulometry between these two DEs. Thus, a DE treatment of 1000 ppm was shown to provide long-term protection of wheat and maize against S. oryzae, but this is strongly dependent on the DE formulation, commodity, and insect species. Overall, such natural resource-based inert silicaceous deposits could be used with success in stored-product protection with only some minor modifications, such as sieving and drying of the raw deposit.

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BACKROUND: Stored product protection from insect pests relies heavily on the use of phosphine. The most serious drawback of phosphine is the development of resistance in major stored product insects worldwide, including the red flour beetle, Tribolium castaneum (Herbst) and the lesser grain borer, Rhyzopertha dominica (F.). Two genetic loci are responsible for phosphine resistance: the rph1 (S349G mutation in the cyt-b5-r homolog) in T. castaneum and the rph2 (P45/49S mutation in the dihydrolipoamide dehydrogenase (dld) gene) in T. castaneum and R. dominica. RESULTS: In this study, we have developed and applied high-throughput, practical and specific molecular diagnostics (TaqMan qPCR) for monitoring mutations S349G, P45S and P49S. In our pilot monitoring application, we have included phosphine-resistant and susceptible populations from different parts of the world (USA, Australia, Brazil) and European strains from Greece and Serbia. Our results for the resistant T. castaneum showed a P45S mutant allele frequency (MAF) of 100% and 75.0% in the populations from Serbia and Brazil, respectively. Regarding the susceptible T. castaneum, P45S was detected in Greece (MAF = 62.5%) and was absent in Australia (MAF = 0.0%). Additionally, the S349G mutation was found to be fixed in all resistant populations, while it was also detected in susceptible ones (frequencies: 65.0% and 100.0%). The only case where both mutations were fixed (100%) was a resistant population from Serbia. In R. dominica, the P49S mutation was found only in the two resistant R. dominica populations from Serbia and Greece (50.0% and 100%) and was absent from the susceptible one from Greece; thus, P49S seems to be a satisfactory indicator for monitoring phosphine resistance. CONCLUSIONS: Our P49S detection assay in R. dominica seems to be a viable option in this direction, yet its utilization needs additional large-scale confirmatory work. The identification of additional resistance markers also should be prioritized. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

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OBJECTIVE: Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) originating from South America is one of the important insect pests that damages storage products and is found on every continent. There is a new interest in using enthomopathogens for microbial control of P. interpunctella as well as other stored product pests. Coccidia as a group of protistan entomopathogens are host specific and their pathogenic effects on the hosts are more pronounced. Although this pathogenic effect results in increased host mortality or higher susceptibility to insecticides, the suppressive potential of coccidia in natural populations has not been adequately studied. In this study, characterization, distribution and occurrence of a coccidian entomopathogen was aim to show its natural suppressing potential in P. interpunctella populations. METHODS: During the three years (from 2019 to 2021), a total of 3.432 P. interpunctella samples (2.047 dead and 413 living larvae, 932 adults and 40 pupae) were collected from fourteen populations. After macroscopic examination, suspected samples were dissected in Ringer's solution and then prepared wet smears including host fat body were examined for presence of coccidian pathogens under a light microscope at a magnification of 400-1000X. The oocysts of the coccidian were measured and photographed using a microscope with a digital camera and soft imaging system. RESULTS: The pathogen was observed in the fat bodies of the larvae, pupae and adults. Oocysts measured as 29.52±3.32 (25.27- 35.08) µm in diameter and they include 8 sporocysts. Sporocysts measured as 9.11±0.61 (8.90-9.85) µm. Forty-five of 3.432 P. interpunctella larvae, pupae and adults were found to be infected. Coccidian infections have also reached to the levels that can be considered high in some populations, as significant as 29.2%. The infection was observed in the three (21.4%) of the examined fourteen populations. CONCLUSION: The coccidian entomopathogen presented in this study is the first Adeleid coccidian record from P. interpunctella populations in Türkiye. The detection of Adelina mesnili Perez (Coccidia: Adeleidae) in at least three populations and the infection rate reaching 29.2 percent, confirms that this pathogen has a considerable effect P. interpunctella populations that cannot be underestimated. Our results confirm that the coccidian pathogen is very effective in the larval stage.

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Phosphine is globally the most widely adopted fumigant for the control of storage pests. Recently, an increase in the frequency of stored-product pest resistance has been observed with significant geographical and interspecific variations. In this context, there are available data for the occurrence of resistant populations from America, Asia, Africa, and Australia, but there are few data in the case of Europe. Therefore, the aim of this work was to evaluate phosphine efficacy in important beetle pests of stored products, i.e., Sitophilus oryzae (L.), Oryzaephilus surinamensis (L.), and Rhyzopertha dominica (F.) sampled from the Czech Republic, using a rapid diagnostic test that is based on the speed to knockdown after exposure. Apart from the standard laboratory populations, which were used as the controls, we tested 56 field populations of these three species, collected in Czech farm grain stores. The survey revealed that 57.1% of the tested field populations were classified as phosphine-susceptible, based on the knockdown method used. However, profound variations among species and populations were recorded. The species with the highest percentage of resistant populations was R. dominica (71.4% of the populations; resistance coefficient 0.5-4.1), followed by S. oryzae (57.1% of the populations; resistance coefficient 0.8-6.9), and O. surinamensis (9.5% of the populations; resistance coefficient 0.5-2.9). Regarding the intra-population variability in response to phosphine (slope of the knockdown time regression), the laboratory and slightly resistant populations of all species were homogenous, whereas the most resistant populations were strongly heterogeneous. Our data show that the occurrence of resistance in the Czech Republic is relatively widespread and covers a wide range of species, necessitating the need for the adoption of an action plan for resistance mitigation.

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The lesser grain borer Rhyzopertha dominica is the major pest of stored paddy rice globally, including in Taiwan. It has strong phototaxis and is good at flying, suitable for developing a light-trapping method to monitor and control it. In the present study, a wavelength of light-emitting diodes (LEDs), i.e., 373 nm, was determined to be the most efficient to trap R. dominica using a dodecagon maze. Accordingly, an LED trap, named the Taiwan Agricultural Research Institute-LED (TARI-LED) trap, was invented, which comprised LEDs of two distinct wavelengths (373 and 408 nm), a wavelength switch, a suction fan, and an insect collector. The trapping efficiency was assessed in a 4-m3 laboratory arena and two paddy rice storehouses. An initial assessment was performed in the laboratory arena and showed that the TARI-LED trap with 373-nm wavelength for R. dominica rapidly increased in the first 30 min, reaching the highest trapping rate (68.5%) after 3 h. In addition, no significant difference was observed between the suction fan turned on or off. The field tests showed that the 373-nm wavelength had the highest effectiveness for trapping R. dominica in the two paddy rice storehouses, and no significant difference was observed in the number of R. dominica trapped by the 373-nm TARI-LED trap or the CDC-UV light trap. In conclusion, our TARI-LED trap 373 nm exhibited high efficiency in trapping R. dominica in paddy rice storehouses. Moreover, a suction fan-free design should benefit long-term and safe use in paddy rice storehouses trapping R. dominica.

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BACKGROUND: Silo bag is a major harvest storage option in many countries worldwide. Wildlife interacts with this new element in the rural landscape. As a result, wildlife activity could generate breaks in silo bag lining, causing losses to the stored content. The aim of this study was to analyze the damage in silo bags by large hairy armadillos (Chaetophractus villosus) according to different spatial arrangements of silo bags, in order to propose a management strategy to reduce the damage. Our prediction was that silo bags arranged in a cluster would have less damage by large hairy armadillos than bags arranged in a row or than single (isolated) bags at a certain plot. In addition, we expected that in a cluster the exposed outside of the bags would show increased damage compared to the inside of the cluster. RESULTS: We measured 294 silo bags. Damage intensity (number of breaks/100 m silo bag perimeter) in silo bags arranged in a cluster was 72% lower than in bags arranged in a row (P = 0.03), and 77% lower than in single bags (P = 0.001). Moreover, we detected that damage intensity inside was 75% lower than outside of a cluster (P = 0.001). CONCLUSION: We propose grouping in a cluster of parallel bags instead of installing them in a row or isolated bags at plot as a strategy that could be adopted and implemented by farmers in order to reduce the damage by large hairy armadillos, the most harmful wildlife species to silo bags in Argentina. © 2021 Society of Chemical Industry.

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The development of biologically based approaches for stored product pest control is needed to reduce chemical inputs. Bioassays were performed to investigate host habitat location in the trophic interaction durum wheat/Rhyzopertha dominica/Theocolax elegans. GC-MS analyses were carried out to identify some chemical compounds produced by the host-related substrates. Choice and no-choice experiments demonstrated that female parasitoids were poorly attracted to intact kernels with respect to the infested substrates. Furthermore, T. elegans females performed longer residence time on infested wheat, and they generally displayed a short-term like fidelity for this cue, remaining on it during the whole observation. Infested wheat emitted one chemical (fenchone), which is possibly linked to host larvae presence, while the feces produced by host larvae emitted some other characteristic compounds. Results demonstrated that the presence of host larvae is a key factor for T. elegans host habitat location, considering that the attractiveness of the undamaged wheat is irrelevant. Furthermore, parasitoid females tended to stay on attractive cues, limiting the risk of contamination of other commodities. Biological control tools may be useful to improve the efficiency of pest management programs, but their application should be carefully evaluated.

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In the present work, we evaluate the toxic and repellent properties of lemongrass (Cymbopogon citratus (DC. ex Nees) Stapf.) essential oil and its components against Sitophilus granarius Linnaeus as an alternative to insecticide use. The lethal dose (LD50 and LD90), survivorship, respiration rate, and repellency on adults of S. granarius exposed to different doses of lemongrass oil and some of its components were evaluated. The chemical composition of the essential oil was found to have the major components of neral (24.6%), citral (18.7%), geranyl acetate (12.4%), geranial (12.3%), and limonene (7.55%). Lemongrass essential oil (LD50 = 4.03 µg·insect-1), citral (LD50 = 6.92 µg·insect-1), and geranyl acetate (LD50 = 3.93 µg·insect-1) were toxic to S. granarius adults. Survivorship was 99.9% in insects not exposed to lemongrass essential oil, decreasing to 57.6%, 43.1%, and 25.9% in insects exposed to LD50 of essential oil, citral, and geranyl acetate, respectively. The insects had low respiratory rates and locomotion after exposure to the essential oil, geranyl acetate, and citral. Our data show that lemongrass essential oils and their components have insecticidal and repellent activity against S. granarius and, therefore, have the potential for application in stored grain pest management schemes.

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This study evaluated the fumigant ethanedinitrile (EDN) against the cigarette beetle, Lasioderma serricorne, and phosphine-resistant and susceptible lesser grain borer, Rhyzopertha dominica, life stages under laboratory conditions. Eggs of both species were the most susceptible stage to EDN. EDN is, therefore, a promising alternative because eggs are generally tolerant to most common fumigants. Lasioderma serricorne eggs were the most susceptible with an LC50 estimated of 50.4 ppm, followed by adults, pupae and larvae with LC50 values of 160.2, 192.5, and 446.6 ppm, respectively, after 24-h exposure at 25°C. Eggs of phosphine-susceptible (LC50 = 11.2 ppm) and resistant (LC50 = 12.0 ppm) R. dominica strains were more susceptible to EDN than were adults of both strains, with LC50 values of 27.7 and 36.0 ppm, respectively. Lasioderma serricorne mixed life stage cultures were completely controlled at concentrations ≥2,000 ppm at 24 h. Fumigation with 600 ppm was enough to suppress adult emergence in the case of the phosphine-susceptible R. dominica strain (USDA), while an average of only 4.0 adults emerged from the phosphine-resistant R. dominica strain (Belle Glade) compared with 514.3 adults in the control. Lasioderma serricorne was more tolerant to EDN than both R. dominica strains. EDN caused 61.8 and 68.2 % inhibition of R. dominica (USDA) cytochrome c oxidase activity at concentrations of 0.0038 and 0.0076 mM in vitro, respectively, and it did not inhibit its activity in the case of an in vivo assay. These results suggest that cytochrome c oxidase may not be the main target for EDN toxicity.

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Laboratory tests on acclimated and nonacclimated life stages of Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) (adults, pupae, larvae, and eggs) and Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) (adults, larvae, and eggs) were conducted at 0, -5, -10, and -15°C to evaluate effects of acclimation on susceptibility to cold treatment. Acclimation of all tested life stages for 7 d at 15°C affected susceptibility of both species to the cold temperatures. After 1 d exposures for ≥2 h, acclimated adults had a noticeable increase in cold tolerance compared with nonacclimated adults for both tested species. Nonacclimated pupae of T. confusum were equally susceptible to cold compared with acclimated pupae at short exposures to low temperatures. Exposure of nonacclimated life stages of T. confusum, at -10°C for 1 d gave 0% survival. Similarly, almost all (99.6%) nonacclimated individuals of O. surinamensis died at -10°C. At 0°C, nonacclimated larvae were more cold tolerant than acclimated larvae, but this trend was reversed when larvae were exposed to -5°C. Mixed results were obtained for larvae of O. surinamensis because in some of the combinations tested, nonacclimated larvae were more tolerant, even at temperatures that were lower than 0°C. In contrast to O. surinamensis, eggs of T. confusum that had not been exposed to cold were not affected by acclimation, while exposure to cold showed increased cold hardiness in acclimated eggs. Results show that individual stored-product insect species may have mixed susceptibility to cold temperatures, which must be taken into account when using cold treatment as a management strategy.

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The objectives of the study are to understand how naïve beetles disperse after emerging as an adult in a homogeneous resource patch. We compared the movement of adult male and female Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) using a laboratory and a field-collected strain during the first 2 d after their emergence from the wheat kernel in which they developed. We first asked if naïve male and female beetles show any innate orientation pattern. Males showed an upward orientation bias during the first day, but not in the second, whereas females had a random pattern of orientation in both days of evaluation. No significant differences were observed between the two strains. Given that males release an aggregation pheromone, we next asked if the upward movement of males improved their ability to be found by a naïve female. The presence of a male, whether above or below a newly emerged female, changed the females' movement direction from random to bias towards the male. In contrast, free-walking males exhibited the same upward movement bias on the first day regardless of the position of the caged male. Only on the second day did male movement change to the opposite direction of the caged male. Here, we report differences between males and females' movement orientation strategies and their response to males producing aggregation pheromone within the grain mass. Our data may improve our understanding of pheromone attraction and help us to develop better monitoring and control tools.

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The lesser grain borer, Rhyzopertha dominica (Fabricius) is a primary pest of starch-containing stored products worldwide. Here, we report characterization of mitogenome of R. dominica and its phylogenetic position. Rhyzopertha dominica complete mitochondrial genome (GenBank accession number MN527959) from Jingziguan town consisted of a circular DNA molecule of 15,862 bp (with 74.36% A + T content). The mitogenome comprised of 13 protein-coding genes (PCGs), and 22 tRNA and two rRNA genes. PCGs had typical ATN (Met) initiation codons and were terminated by typical TAN stop codons.

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The saw-toothed grain beetle, Oryzaephilus surinamensis Linné, is a well-known stored-product insect. Beetles were obtained from Xichuan County and the mitochondrial genome was characterized (GenBank accession number MN535903). The mitogenome consists of a circular DNA molecule of 15,941 bp, with only 27.36% GC content. It comprises 13 protein-coding, 22 tRNA, and 2 rDNA genes. The protein-coding genes have typical ATN (Met) initiation codons and are terminated by typical TAN stop codons.

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Grain stored in bins is initially a relatively homogenous resource patch for stored-product insects, but over time, spatial pattern in insect distribution can form, due in part to insect movement patterns. However, the factors that influence stored-product insect movement patterns in grain are not well-understood. This research focused on the movement of the lesser grain borer, Rhyzopertha dominica (F.), within a simulated wheat grain mass (vertical monolayer of wheat) and the identification of factors that contribute to overall and upward movement (age since adult emergence from an infested kernel [1, 7, and 14 d], sex, strain, and different levels of environment quality). We also used the model selection approach to select the most relevant factors and determine the relationships among them. Three-week-old adults tended to stay closer to the surface compared with 1- or 2-wk-old insects. Also, females tended to be more active and to explore a larger area compared with males. Explored area and daily displacement were also significantly strain-dependent, and increasing grain infestation level decreased daily displacement and explored area. Variation in movement pattern is likely to influence the formation of spatial pattern and affect probability to disperse. Understanding movement behavior within a grain bin is crucial to designing better strategies to implement and interpret monitoring programs and to target control tactics.

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Os inseticidas de origem botânica têm-se mostrado uma alternativa promissora na redução de insetos que atacam grãos armazenados. O objetivo neste trabalho foi avaliar o potencial inseticida de nove espécies vegetais na reprodução de Callosobruchus maculatus (Fabr., 1775) (Coleoptera: Bruchidae). Folhas e ramos das plantas cumaru (Amburana cearensis), marmeleiro (Croton sonderianus), mussambê (Cleome spinosa), jurema-preta (Mimosa tenuiflora), angico (Anadenanthera macrocarpa), pereiro (Aspidosperma pyrifolium), mangirioba (Senna occidentalis), alfazema-brava (Hyptis suaveolens) e juazeiro (Ziziphus joazeiro) foram secos e moídos, separadamente, até obter um pó fino e, posteriormente, aplicados sobre amostras de grãos de feijão-caupi (45 g) contidas em copos plásticos (100 mL). Cada amostra foi infestada com um casal recém-emergido de C. maculatus e registrada a oviposição de cada fêmea. Grãos infestados, mas sem adição de pó foram utilizados como testemunha. O estudo foi realizado em delineamento inteiramente casualizado com cinco repetições, em arranjo fatorial 9 x 2 + 1, correspondente às espécies de plantas, tipos de pó e testemunha, respectivamente. Para cada tratamento foi avaliado o número total de ovos por fêmea, o número de adultos emergidos e a razão sexual de C. maculatus. A sobrevivência dos adultos não foi afetada pela presença de pó quando comparada à testemunha. A média total de ovos variou entre 68,7 e 85,3 e não foi diferente entre os tratamentos. Contudo, grãos tratados com pó de folhas de mussambê e pó de ramos de juazeiro e pereiro tiveram a menor emergência de adultos (entre 68,1 e 70,9%). De forma semelhante, a razão sexual de C. maculatus foi reduzida em grãos tratados com pó de folhas de mussambê e pó de ramos das espécies jurema-preta, angico e pereiro com, aproximadamente, 40% de fêmeas a menos.

Botanical insecticides have been employed successfully against some stored product insects. In this study, the insecticidal potential of nine plant species was evaluated on the reproduction of Callosobruchus maculatus (Fabr., 1775) (Coleoptera: Bruchidae). Leaves and stems of "cumaru" (Amburana cearensis), "marmeleiro" (Croton sonderianus), "mussambê" (Cleome spinosa), "jurema-preta" (Mimosa tenuiflora), "angico" (Anadenanthera macrocarpa), "pereiro" (Aspidosperma pyrifolium), "mangirioba" (Senna occidentalis), "alfazema-brava" (Hyptis suaveolens) and "juazeiro" (Ziziphus joazeiro) were dried and ground, separately, into a fine powder which was thoroughly mixed with 45 g of cowpea beans in a plastic cup (100 mL). Each sample was infested with a pair of newly emerged C. maculatus and the numbers of eggs and emerged adults and sex ratio were registered. Infested cowpea grains without any powder were used as a control treatment. The experiment was carried out in completely randomized design with five replicates in a factorial arrangement of 9 x 2 + 1, corresponding to plant species, types of powders and control treatment, respectively. Powders from different plant species have not significant effect on survival of C. maculatus adults when compared with the control. Similarly, the total number of eggs was not different between plant species studied and this number ranged between 68.7 and 85.3 eggs per female. However, powder from "mussambê" leaves or "juazeiro" and "pereiro" stems had the lowest adult emergence between 68.1% and 70.9%. With regard to sex ratio of C. maculatus, powder from "mussambê" leaves and that from "jurema-preta", "angico" and "pereiro" stems reduced the number of female emerged in approximately 40%.

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Toxic effects of essential plant oils in adult Sitophilus oryzae (Linnaeus) (Coleoptera, Curculionidae). Stored grains are subject to losses in quality nutritional value and in sanitation from the time they are stored to the time they are consumed. Botanical insecticides may offer an alternative solution for pest control. The objective was to test the insecticidal properties of the essential oils of Cymbopogon citratus (leaf), Zingiber officinale (root) and Mentha sp. (leaf). The efficacy of these oils was tested to control the rice weevil, S. oryzae, using hydrodistillation. Chemical analysis of the essential oils was carried out by gas chromatography. Major components of C. citratus were geranial (48 percent) and neral (31 percent), of Z. officinale were α-zingibereno (13 percent), geranial (16 percent), neral (10 percent) and α-farneseno (5 percent) and of Mentha sp. was menthol (92 percent). Bioassays were carried out by fumigation and topical application. In topical application assays, the essential oil of C. citratus had greater toxicity (LC50 0.027 µL mL-1) and shorter exposure time than the oils of the other two plants. After 24 h and 48 h, 70 percent and 100 percent mortality of S. oryzae occurred, respectively. In fumigation assays, essential oil of Z. officinale had a lower LC50 (1.18 µL cm-2) and 70 percent mortality after 24 h exposure. Therefore, we recommend the use of essential oils of C. citratus and Z. officinale to control the rice weevil S. oryzae.

Efeito tóxico de óleos essenciais de plantas medicinais em adultos de Sitophilus oryzae (Linnaeus) (Coleoptera, Curculionidae). Grãos armazenados estão sujeitos a perdas na qualidade física, sanitária e nutricional, desde sua maturação fisiológica até o momento do consumo. Uma alternativa para o manejo de pragas são os inseticidas botânicos. O presente trabalho teve como objetivo avaliar o efeito inseticida de óleos essenciais de Cymbopogon citratus (folha), Zingiber officinale (raiz) e Mentha sp. (folha), obtidos através do método de hidrodestilação,no controle de adultos do gorgulho-do-arroz, S. oryzae. A caracterização química dos compostos encontrados nos óleos essenciais foi realizada por cromatografia gasosa, sendo observados como principais componentes para C. citratus: geranial (48 por cento) e neral (31 por cento), para Z. officinale: 16 por cento de geranial, 13 por cento de α-zingibereno, 10 por cento de neral e 5 por cento de α-farneseno e para Mentha sp.: 92 por cento de mentol. Os bioensaios foram realizados por aplicação tópica e fumigação. Os resultados da aplicação tópica mostraram que o óleo essencial de C. citratus apresenta maior toxicidade quando comparado à Mentha sp.e ao Z. officinale, pois apresentou uma CL50 de 0.027 µL mL-2 e um menor período de exposição, causando 70 por cento e 100 por cento de mortalidade de adultos de S. oryzae, respectivamente, 24 e 48 horas após dos tratamentos. Nos ensaios com fumigação, em adultos de S. oryzae, o óleo essencial de Z. officinale, apresentou a menor CL50 (1,18 µL cm-2) e o menor período de exposição, causando 70 por cento de mortalidade em 24 horas após a aplicação dos tratamentos. Desse modo conclui-se que os óleos de C. citratus e Z. officinale podem ser recomendados no controle de adultos do gorgulho-do-arroz S. oryzae.

RESUMO

With the purpose of verifying the occurrence of insect pests in dog food commercialized in the Metropolitan Region of Recife, samples from 15 different pet stores were submitted to the extraction of insects in a Berlese-Tullgren apparatus. Tribolium castaneum (Herbst) (Tenebrionidae) (55.2 percent) was the most frequent specie followed by Oryzaephilus surinamensis (L.) (Cucujidae) (31.3 percent), Rhyzopertha dominica (Fabricius) (Bostrichidae) (8.9 percent) and Lasioderma serricorne (Fabricius) (Anobiidae) (4.7 percent), all from Coleoptera. Recife showed the highest rate of infestation (53.6 percent), followed by Olinda (34.4 percent) and Jaboatão dos Guararapes (12.0 percent). The infestation by coleopters in the region occurs with high frequency and may represent a threat mainly in commercialized products in bulk.

Objetivando verificar a ocorrência de insetos-praga em alimento industrializado para cães, comercializado na região metropolitana do Recife, amostras de 15 diferentes lojas agropecuárias foram submetidas à extração de insetos em funil de Berlese-Tullgren. Tribolium castaneum (Herbst) (Tenebrionidae) (55,2 por cento) foi o mais freqüente, seguido por Oryzaephilus surinamensis (L.) (Cucujidae) (31,3 por cento), Rhyzopertha dominica (Fabricius) (Bostrichidae) (8,9 por cento) e Lasioderma serricorne (Fabricius) (Anobiidae) (4,7 por cento), todos Coleoptera. Recife apresentou o maior índice de infestação (53,6 por cento), seguido por Olinda (34,4 por cento) e Jaboatão dos Guararapes (12,0 por cento). A infestação por coleópteros ocorre com elevada freqüência na região, podendo representar uma ameaça principalmente nos produtos comercializados a granel.

Assuntos